Quidditch is the main sport of the wizarding community. It is followed by wizards in much the same way that football (soccer) is followed by Muggles. Harry initially compares it to basketball on broomsticks with three hoops. It is a fast-paced, dangerous game played by two teams with seven members each and officiated by one referee. Typically there are no player substitutions allowed in the course of the game.

3 Chasers - their job is to score goals. Their responsibility is passing the Quaffle amongst themselves so as to be able to throw it through one of the adversaries' three hoops (or goal posts) in the field, while trying to keep it out of the hands of the opposing team's Chasers. A goal is worth 10 points.

1 Keeper - Stationed at their team's goalpost, his job is to guard the goal posts and keep the opposite team from scoring.

2 Beaters - their job is to protect their team, including themselves, from the Bludgers, and to hit the Bludgers into their rivals. They use a small bat, like the bat in Rounders, or a small baseball bat, to hit the Bludgers.

1 Seeker - his job is to catch the small Golden Snitch before the rival team's Seeker catches it. When the Golden Snitch is caught, the game is finished; catching the Snitch is worth one hundred and fifty points. Seekers "are usually the smallest and fastest" members of the team "and most serious Quidditch accidents seemed to happen to them."

Broomsticks (7 per side) - the best one should go, if possible, to the Seeker

Quaffle (1) - "a bright red ball about the size of a soccer ball; the chasers throw the Quaffle to each other and try and get it through one of the hoops to score a goal. Ten points every time the Quaffle goes through one of the hoops."

Golden Snitch (1) - "tiny, about the size of a large walnut. [It is] bright gold and [has] little fluttering silver wings. It's the most important ball of the lot. It's very hard to catch because it's so fast and difficult to see."

Bats (2 per side) - used by the Beaters to knock Bludgers away from their team and into their opponents.

the game ends only when the Golden Snitch is "caught, so it can go on for ages";

substitutions are seldom allowed; when one World Cup match went on for several weeks, it was worthy of comment that they had to get substitutes so that the players could get some rest;

there are seven hundred ways to foul in the game "and all of them had happened during a World Cup match in 1473"; a foul is answered with a penalty shot by the fouled player or by one of the Chasers (when the Keeper or Seeker is fouled).

Much like with Muggle sports, there are professional regional teams, and the best players of the regional teams are then tapped for the national team. We are told that the English national team were eliminated from the World Cup by Transylvania in Harry Potter and the Goblet of Fire, and that Scotland had lost to Luxembourg, and Wales to Uganda, in that year's World Cup competition. This leaves Ireland to defend the honour of the British Isles against Romania, which it does quite ably. It is interesting to note that the national boundaries for Quidditch do not follow modern political lines.

The book Quidditch Through the Ages by "Kennilworthy Whisp" mentions that there are 13 regional teams in Britain and Ireland. Of these, mention in the main books is made of the following five:

The Chudley Cannons, Ron's favorite team. Ron bemoans their standing, last in the league, and the bad decisions made by their management in trading players. Professor Dumbledore actually mentions their dismal prospects once as well.

The Holyhead Harpies, famous for always fielding a team made up entirely of witches. Professor Slughorn mentions that one of his ex-students is on that team, and she is present at the Slug Club Christmas party, though Harry does not see her. In a post-publication interview, the author said that Ginny Weasley played for the Harpies after graduation.

Puddlemere United is the team that Oliver Wood plays for after graduation.

The Wimbourne Wasps fielded Ludo Bagman as a Beater, arguably the best Beater they had ever had, and Ludo keeps hearkening back to his days on the team, even wearing his old Quidditch robes to the Quidditch World Cup.

The Tutshill Tornados are Cho Chang's favorite Quidditch team, one she has supported since she was six years old. In 1995, they won the British and Irish Quidditch League. Ron hates this team and resents the fact that many of its erstwhile fans started supporting it only when the Tornados won the league.

From the beginning, Harry feels as if he is something of a fraud. The Boy Who Lived — yes, he's famous, but not through anything he had done himself, really; yes, he lived, and Lord Voldemort vanished, but it wasn't anything he had done, he was simply there when all this magic flowed around him, and since then he had lived in an environment where the magic was suppressed, even beaten out of him. He felt, from the beginning, intimidated both by wizards' children like Ron, who had grown up with magic as a matter of course, and Hermione, Muggle-born as Harry himself had been Muggle-reared, but who had, upon learning that she was a witch, promptly purchased and read all of the first-year textbooks and several others besides, with her parents' support. And he discovers flying, which he can do well, and it is good; and then he discovers that he is an excellent Seeker, and he becomes the star and the center of the house Quidditch team, and it is a source of confidence to him. It also is a tie back to his father, who was equally an excellent Quidditch player in his days at Hogwarts.

It is through Quidditch that Harry achieves some of his greatest victories, winning the Quidditch Cup in his third year, coming to the notice of Cho Chang in that same year, and coaching the Gryffindor team to another victory in his sixth year. Ron, in the same way, sees benefits from his Quidditch experience: starting off as a poor player ("the best of a bad lot" according to then-Captain Angelina Johnson), Ron gains the confidence he needs to tend goal properly. This confidence will show up again in later books.

The scoring of Quidditch matches may seem unbalanced since the 150 points from catching the Snitch often overwhelms the 10 points per goal, but it is arguably considerably harder to catch the Snitch than to score a goal with the Quaffle. Quidditch at the school is played in series, so that each point counts toward ultimate victory. There have been matches where Harry (or his replacement Seeker Ginny Weasley, in Harry Potter and the Half-Blood Prince) waited until Gryffindor was ahead by a certain number of goals so that when he caught the Snitch, Gryffindor would have enough overall points to win the Quidditch Cup. It appears that winning the Quidditch Cup is a large, though not overwhelming part, of winning the House Cup; we are never, however, told how many House points winning the Quidditch Cup gains for the winning team.

There are several unanswered questions about Quidditch matches. One of the big ones has to do with the bludgers. They are bewitched to go after the players, but what stops them? Even when play is stopped, for a penalty or conference, the bludgers must go on trying to hit the players. Thus in theory, a penalty shot could be disrupted by a bludger, or a bludger could disable the referee, and the Beaters can never take a break, they have to be tracking the bludgers until they are safely returned to the crate at the end of the game. The most logical solution to this issue is to have the Bludgers charmed to not go after people on the ground just as they don't target people in the stands. As conferences and time outs are on the ground, this would allow the Beaters a break. Against this, however, we have the behaviour of the bludger when Oliver Wood was explaining the rules of the game to Harry; released from the crate, the bludger attacked Harry who, despite being on the ground, had to knock it away with his bat, and also attacked Oliver who caught it and returned it to he crate.

Quidditch is an interesting game, in that it emphasizes both team and individual abilities in the separate playing positions. The Chasers act as a team, passing the ball between themselves, acting as a group to capture the ball from the opposing team, scoring goals against the opposing Keeper and defending their own. The Beaters also act as a team, keeping the Bludgers away from their own team and arranging their interference with the other team. The Seeker, generally orbiting high above the main game, is a solo performer, chasing down and capturing the minuscule Snitch. As such, a game of Quidditch could be seen as three games in one: a game of Chasers and Keeper, a game of Beaters, and a game of Seekers, all occurring on the same pitch at the same instant.

Intermediate warning: Details follow which you may not wish to read at your current level.

It is not too surprising that Harry's identity is somewhat defined by his abilities at Quidditch – he recognizes that a thing he is good at is flying, and this is reinforced in Harry Potter and the Goblet of Fire, first by Professor Moody pointing it out to him in the lead-in to the First Task of the Triwizard Tournament, and then by Ludo Bagman's fulsome compliments in the commentating for that event. One wonders, then, why Harry does not follow Quidditch in the Daily Prophet, tossing away Prophets after glancing at the front page, throughout the summer before his fifth year, and why he does not seem to miss Quidditch during his seventh year. It is possible that Quidditch is primarily a means by which he can get more flying time. Once his Firebolt is destroyed, it is possible that he simply sets aside his hopes of flying until his job, the destruction of Voldemort, is done. However, it still seems odd that Quidditch can be so all-consuming at school, and ignored through the summer.

It is possible that Quidditch fades as the center of Harry's life over time as he gains confidence in his other magical abilities. Quidditch, and the associated flying abilities, are central to Harry's self-image in his early years, as it is here that he first is able to demonstrate competence that is truly his own, rather than provided by events in which he took no conscious part. Over the course of the story, however, we can see that Harry gains abilities and strengths of his own outside Quidditch, in his battles against Death Eaters and against Voldemort himself. This is highlighted by Harry's very different reactions to the loss of his Nimbus 2000 broom in Harry Potter and the Prisoner of Azkaban, and to the loss of his Firebolt in Harry Potter and the Deathly Hallows. The former was devastating, as we would expect from Harry's having made Quidditch central to his self-image; the latter is simply buried under other losses and more or less forgotten. By this time, also, rather than defining himself by his broom and his abilities with it, Harry seems to have defined himself by his wand and his abilities with that; when Harry's wand is accidentally broken, his reaction is similar to that which follows the loss of his Nimbus 2000.